267 research outputs found
The origin of organic emission in NGC 2071
Context: The physical origin behind organic emission in embedded low-mass
star formation has been fiercely debated in the last two decades. A multitude
of scenarios have been proposed, from a hot corino to PDRs on cavity walls to
shock excitation.
Aims: The aim of this paper is to determine the location and the
corresponding physical conditions of the gas responsible for organics emission
lines. The outflows around the small protocluster NGC 2071 are an ideal testbed
to differentiate between various scenarios.
Methods: Using Herschel-HIFI and the SMA, observations of CH3OH, H2CO and
CH3CN emission lines over a wide range of excitation energies were obtained.
Comparisons to a grid of radiative transfer models provide constraints on the
physical conditions. Comparison to H2O line shape is able to trace gas-phase
synthesis versus a sputtered origin.
Results: Emission of organics originates in three spots: the continuum
sources IRS 1 ('B') and IRS 3 ('A') as well as a outflow position ('F').
Densities are above 10 cm and temperatures between 100 to 200 K.
CH3OH emission observed with HIFI originates in all three regions and cannot be
associated with a single region. Very little organic emission originates
outside of these regions.
Conclusions: Although the three regions are small (<1,500 AU), gas-phase
organics likely originate from sputtering of ices due to outflow activity. The
derived high densities (>10 cm) are likely a requirement for organic
molecules to survive from being destroyed by shock products. The lack of
spatially extended emission confirms that organic molecules cannot (re)form
through gas-phase synthesis, as opposed to H2O, which shows strong line wing
emission. The lack of CH3CN emission at 'F' is evidence for a different history
of ice processing due to the absence of a protostar at that location and recent
ice mantle evaporation.Comment: 10 Pages, 8 figures, Accepted for Astronomy and Astrophysic
The JCMT Gould Belt survey: Dense core clusters in Orion B
The James Clerk Maxwell Telescope Gould Belt Legacy Survey obtained SCUBA-2 observations of dense cores within three sub-regions of OrionB: LDN1622, NGC2023/2024, and NGC2068/2071, all of which contain clusters of cores. We present an analysis of the clustering properties of these cores, including the two-point correlation function and Cartwright’s Q parameter. We identify individual clusters of dense cores across all three regions using a minimal spanning tree technique, and find that in each cluster, the most massive cores tend to be centrally located. We also apply the independent M–Σ technique and find a strong correlation between core mass and the local surface density of cores. These two lines of evidence jointly suggest that some amount of mass segregation in clusters has happened already at the dense core stage
Distributed Model-to-Model Transformation with ATL on MapReduce
International audienceEfficient processing of very large models is a key requirement for the adoption of Model-Driven Engineering (MDE) in some industrial contexts. One of the central operations in MDE is rule-based model transformation (MT). It is used to specify manipulation operations over structured data coming in the form of model graphs. However, being based on com-putationally expensive operations like subgraph isomorphism, MT tools are facing issues on both memory occupancy and execution time while dealing with the increasing model size and complexity. One way to overcome these issues is to exploit the wide availability of distributed clusters in the Cloud for the distributed execution of MT. In this paper, we propose an approach to automatically distribute the execution of model transformations written in a popular MT language, ATL, on top of a well-known distributed programming model, MapReduce. We show how the execution semantics of ATL can be aligned with the MapReduce computation model. We describe the extensions to the ATL transformation engine to enable distribution, and we experimentally demonstrate the scalability of this solution in a reverse-engineering scenario
Treatment with Idelalisib in Patients with Relapsed or Refractory Follicular Lymphoma: The Observational Italian Multicenter FolIdela Study
Follicular lymphoma (FL) is an indolent hematological disease, often responsive to the first line of treatment, but characterized by repeated relapses. The therapeutic algorithm for relapsed/refractory FL patients comprises phosphatidylinositol 3-kinase inhibitors. Idelalisib showed anticancer activity, while inducing a significant rate of toxicities. Since the evidence in the literature on its use in normal clinical practice is scarce, a retrospective multicenter study was conducted to evaluate effectiveness and tolerability in a real-life context. Seventy-two patients with a median age at diagnosis of 57.2 years—mostly with an advanced stage (88.9%) and relapsed to the most recent therapy (79.1%)—were enrolled. The median number of prior therapies was three (20.8% refractory to the last therapy before idelalisib). With a median number of 4 months of treatment, the overall response rate was 41.7% (20.8% complete responses). Median disease-free survival and overall survival were achieved at 8.4 months and at 4 years, respectively. Forty-four percent of patients experienced at least one drug-related toxicity: 6.9% hematological ones and 43% non-hematological. The study confirmed that idelalisib has anticancer effectiveness and an acceptable safety profile in relapsed/refractory FL with unfavorable prognostic characteristics, even in the context of normal clinical practice
Infections in patients with lymphoproliferative diseases treated with targeted agents: SEIFEM multicentric retrospective study
We describe the opportunistic infections occurring in 362 patients with lymphoproliferative disorders treated with ibrutinib and idelalisib in clinical practice. Overall, 108 of 362 patients (29·8%) developed infections, for a total of 152 events. Clinically defined infections (CDI) were 49·3% (75/152) and microbiologically defined infections (MDI) were 50·7% (77/152). Among 250 patients treated with ibrutinib, 28·8% (72/250) experienced one or more infections, for a total of 104 episodes. MDI were 49% (51/104). Bacterial infections were 66·7% (34/51), viral 19·6% (10/51) and invasive fungal diseases (IFD) 13·7% (7/51). Among the 112 patients treated with idelalisib, 32·1% (36/112) experienced one or more infections, for a total of 48 episodes. MDI were 54·2% (26/48). Bacterial infections were 34·6% (9/26), viral 61·5% (16/26) and IFD 3·8% (1/26). With ibrutinib, the rate of bacterial infections was significantly higher compared to idelalisib (66·7% vs. 34·6%; P = 0·007), while viral infections were most frequent in idelalisib (61·5% vs. 19·6%; P < 0·001). Although a higher rate of IFD was observed in patients treated with ibrutinib, the difference was not statistically significant (13·7% vs. 3·8% respectively; P = 0·18). Bacteria are the most frequent infections with ibrutinib, while viruses are most frequently involved with idelalisib
The JCMT Gould Belt Survey: Evidence for radiative heating in Serpens MWC 297 and its influence on local star formation
We present SCUBA-2 450micron and 850micron observations of the Serpens MWC
297 region, part of the JCMT Gould Belt Survey of nearby star-forming regions.
Simulations suggest that radiative feedback influences the star-formation
process and we investigate observational evidence for this by constructing
temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two
component model of the JCMT beam for a fixed dust opacity spectral index of
beta = 1.8. Within 40 of the B1.5Ve Herbig star MWC 297, the submillimetre
fluxes are contaminated by free-free emission with a spectral index of
1.03+-0.02, consistent with an ultra-compact HII region and polar winds/jets.
Contamination accounts for 73+-5 per cent and 82+-4 per cent of peak flux at
450micron and 850micron respectively. The residual thermal disk of the star is
almost undetectable at these wavelengths. Young Stellar Objects are confirmed
where SCUBA-2 850micron clumps identified by the fellwalker algorithm coincide
with Spitzer Gould Belt Survey detections. We identify 23 objects and use Tbol
to classify nine YSOs with masses 0.09 to 5.1 Msun. We find two Class 0, one
Class 0/I, three Class I and three Class II sources. The mean temperature is
15+-2K for the nine YSOs and 32+-4K for the 14 starless clumps. We observe a
starless clump with an abnormally high mean temperature of 46+-2K and conclude
that it is radiatively heated by the star MWC 297. Jeans stability provides
evidence that radiative heating by the star MWC 297 may be suppressing clump
collapse.Comment: 24 pages, 13 figures, 7 table
The JCMT Gould Belt Survey: A First Look at the Auriga–California Molecular Cloud with SCUBA-2
We present 850 and 450 μm observations of the dense regions within the Auriga–California molecular cloud using SCUBA-2 as part of the JCMT Gould Belt Legacy Survey to identify candidate protostellar objects, measure the masses of their circumstellar material (disk and envelope), and compare the star formation to that in the Orion A molecular cloud. We identify 59 candidate protostars based on the presence of compact submillimeter emission, complementing these observations with existing Herschel/SPIRE maps. Of our candidate protostars, 24 are associated with young stellar objects (YSOs) in the Spitzer and Herschel/PACS catalogs of 166 and 60 YSOs, respectively (177 unique), confirming their protostellar nature. The remaining 35 candidate protostars are in regions, particularly around LkHα 101, where the background cloud emission is too bright to verify or rule out the presence of the compact 70 μm emission that is expected for a protostellar source. We keep these candidate protostars in our sample but note that they may indeed be prestellar in nature. Our observations are sensitive to the high end of the mass distribution in Auriga–Cal. We find that the disparity between the richness of infrared star-forming objects in Orion A and the sparsity in Auriga–Cal extends to the submillimeter, suggesting that the relative star formation rates have not varied over the Class II lifetime and that Auriga–Cal will maintain a lower star formation efficiency
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